Leonard kebler



I..'KEBLER.

RHI-208ML APPLICATION FILED FEB. Il. I9I9.

Patented N ov. 11, 1919,

awww/to@ Wwf M a@ www I UNITED STATES PATENT OFFICE.

LEONARD KEBLER, OF BRONXVILLE, NEW YORK, ASSIGNOR TO WARD LEONARD RHEOSTAT.

Specification of Letters latent.

Patented Nov. 11, 19,19.

Application filed February 11, 1919. Serial No. 276,391.

To all 'whom t may concern:

Be it known that LLEONARD KEBLER, a citizen of the United States, residing at Bronxville, in the county of Westchester and State of New York, have invented certain new and useful Improvements in Rheestats, of which the following is a specification.

The principal objects of my invention are to provide a new and improved enameled metal base rheostat and a method of making the same. Another object of my invention is to prepare a suitable insulating coat on the metal base of such a rheostat upon which the resistance conductors will be carried. All these objects and others will be appreciated from the following disclosure of specificv ractiee in accordance with my invention. t will be understood that modifications can be made within the scope of the invention. In the manufacture of rheostats, it is often desirable to employ a cast iron supporting 'base or a base of other suitable metal, on account of its strength and rigidity, but since such a base is a good conductor, it becomes necessary carefully to insulate the resistance conductors therefrom. One mode of doing this has been to apply a coat of some re frac-tory insulating material upon the iron base, then apply theI resistance conductor to this coating and secure it thereto by the ap- Many technical difliculties may be encomitered in this work, for example, if the coating applied to the iron is of the same order of refractoriness as the final coating and there is a resistance conductor between them, then vwhen the apparatus is fired to fix the second laze coating, the first glazed coating may soften to such an extent that the wire may sink down through it and malte contact with the iron.

I have found that very satisfactory and serviceable rheostats can be made in accordance with thc following disclosure. The `drawing is a diagrammatic representation of the assembly of elements making up oneof my improved rheostats.V On the cast iron base 11, I apply a ground coat 12.'- This may be practically infusijble as a whole, being' made'up of an infusible ingredient with an .admixture of glass in minor proportion. This mixture is applied in inely divided dry condition, or it may be mixedup wet and applied a' paste, or sprayed upon the iron base 11. It 1s then allowed to dry, whereupon it will hold its shape sufficiently for the next step of the process. This next step consists in the application in dry powdered form or as a wet spray of a coat of glaze 13. The iron base 11 and the two coats 12 land 13 are then fired at the proper temperature in a muille furnace. The coat 12 balies to form a hard adherent earthenwa're coating, 'but at no stage of the .firing process is the heat sufficient to fuse this coat 12 as a whole. The coat 13 actually fuses, so that u n withdrawal from the furnace and su sequent cooling, it constitutes a genuine adherent glaze coat.

Next I apply another ground coat 14 of the same material as the ground coat 12 and in the same way and on top of this another coat of glazev 15 in the dry powdered condition. Again I fire the assembly in a mulle furnace as before and secure a hard adherent insulating earthenware coating 14 covered by a clear impervious glaze coat 15.

Then I apply the resistance conductor 16 and the termlnals or taps 17 connected theren to, each with a thin toe 18. @ver the parts thus assembled I distribute another coating of powdered enamel 1'9 and re the assembly again as before.v The result gives another clear impervious enamel coat 19 adhering tenaciously to the coat 15 and securing the conductor 16`and tap 17 firmly in placef The provision of two ground coats 12 and 141 with an intermediate glaze coat 13l establishes a very secure insulation ybetween the resistance conductors 16 and the iron -base 11. I may find it preferable on some occasions to lire the -ground couts and the glaze coats separately and successively instead of firingA a ground coat and a glaze coat at the same time.

1. In combination, a metal base,- two glaze coat between them, a resistance condutor outside said coats, and a coat of glaze over said conductor.

2. The method of which consists in ap-` ground coats thereon with an intermediate ros plying a ground coat to 'a metal base, then a glaze coat, then another ground `coat, 'then a resistance conductor' and then another glaze coat, firing u'ter each glaze Cout.

3. lin combination, a metal hase, an atlherent partially viti-ined insulating ground coat thereon, u vitreous insulating cout etlhering to said ground cout, another ground coat similar to that iist mentioned adhering to said vitreous cout, and :i resistance dond-noter protected Jfrom Contact with said metal hase by seid three coats.

t. n combination, a metal bese, two ground Coats thereon with :tn intermediate glaze coat between then'i, e resistance conductor outside said coats, and Ineens to cover said conductor and eecure it in place.

5. ln combination, a metal base, two ground coats thereon with an intermediate glane cout between them, and two more t@lezecoats on the outer groui'id eout with ai resistance conductor between them.

6. The method which consiste` in applying u ground Coat to 'e nietel base, then :t glaze Cout, `then firing, then applying another ground-cont, then another glaze Cout, then tiring again, then applying e resistance eonduetor und another glaze coat und firing ztgaiii.

7. rEhe method el insulating :l nietztl hase which eonsists in applying thereto u cout of mixed fusible and infusihle insulating materiel end then e coat oi fusible insulating material and then ut one tiring partially vitrifying the irst Coat and completely vitriying the second coat.

LEONARD KEBLER. 

